Could be an example of Hanlon’s Razor- Never ascribe to malice that which is adequately explained by stupidity. It’s possible they were amusing themselves with simple dry ice bombs which make loud noises but are relatively harmless....
I’m with you—just boys being boys.
We had a kid walking down the street out front once when a very loud 12 gauge shotgun boom went off.
I called the cops ~ they came ~ caught the kid and said 'not to worry, just m-4s' ~ that's worth about 1/4 stick of dynamite.
They took him to jail!
Years later one of his little buddies, now a convicted interstate auto thief, said 'oh, yeah, I remember that ~ stuck the shotgun in the backseat of my dad's car ~ big shotgun ~ then showed the cops the firecracker'
All of that is in line with Sigmund Freud's statement to the effect that 'sometimes madame a cigar is just a cigar'.
There should be a corollary to that. Never ascribe good intentions to muslims if an evil intent could also be involved.